Rew test speaker port

[denlig]

Originally Posted by OpusOfTrolls

What density of roxul are you using?

OpusOfTrolls,



RHT®80 8.0 lb/ft3 128 kg/m3 2x24x48.


the front middle wall is rockwool 4" with 4" gap, next 2 panels floor to ceiling is 2" rockwool with angle wall and wood slats reflecting away from mix position.

next to that is another 4'' with 4" gap. next to that is a curve oval type bass trap with 2" on wall, 6 big hanger,air gap and 4'' rockwool cover with 2 1/2 wide slats reflecting to back wall and diffuser.

I will make the front with atleast 6-8" rockwool with 6-8" air gap.

[OpusOfTrolls]

That should make the front wall pretty dead. A larger air gap would probably absorb more lows, but it's hard to say.

Don't neglect the side walls. I am thinking it is the cause of the interference around 170.

[denlig]

Originally Posted by OpusOfTrolls

That should make the front wall pretty dead. A larger air gap would probably absorb more lows, but it's hard to say.

Don't neglect the side walls. I am thinking it is the cause of the interference around 170.

I thought about that too, just adding more to the sides . I have 4" with 4" gap on the sides already and when running tones i don't hear increase in bass on the sides. The SPL meter doesn't show any big level changes on the side wall.As of now i have quit a lot of woods slat and a diffuser to keep it from dead.I will check as i go and if i have to do the sides i will.

I will keep all the wood slats and just extend the existent framing out and then add rock wool, then the slats back.It shouldn't be that much work to extend the framing out in sections.

SBIR is most likely the problem I'm having.

Thank you.

[OpusOfTrolls]

Originally Posted by DanDan

Bruel and Kjaer, Measuring Sound Handbook:-

experiments have shown that at frequencies around 400Hz, reflections from a person may cause anomalies of up to 6dB

Okay, I have been thinking about this and it seems logical to say, both are very informative. If measuring system response, one would want to be out of the room completely. Then, to see what effect a listener's body would have while being in the room, to see what the ears are hearing, above and behind the head, with clear line of sight to the speakers, is a good choice. While it does not pick up earlobe resonance, it does catch the bulk of everything else. A person's body can absorb sound just as anything, in different unpredictable ways. Those frequency anomalies are part of the sound experience, unless using headphones.

[DanDan]

Den, there is no need to restrict the range of the sweep, although it might make things slightly quicker.
I would normally take a full range sweep, the default setting.
You can then view the full response of the room, or any tiny portion in great detail.
Your now graphs look uncannily smooth. I see no big wide dip.
However we can just about see a dip just below 150, which changes level and frequency with speaker movement.
As the speaker moves away from the front wall, (towards the back wall) the frequency rises.
If this null were due to FWBIR the frequency would drop with away movement.
Back Wall BIR, Floor and Side Wall BIR will show frequency rise with movement towards the mic.
Imagine a snooker shot between the mic, floor/wall, and tweeter.
Move the speaker along that axis towards say the side wall. Let's see if the frequency shifts.
You could also be able to see the actual reflections in the ETC.


DD

[denlig]

Hi Guy's,

Been redoing front wall designs to move my speakers close to the front wall and I'm calling it done. I'm getting tired now and will finish up with hardware eq on the speakers just -3/+3db tops in problems freq area. I have done countless measures and theses measures was the flattest i could get it. I also measure the mixcubes and settle on the position their at with best freq respond.

I started first build with soffit mount but the measurements was awful so i removed it. The studio was not design for sofftits so removing it was a good choice. The front wall build i have now with the speaker placement sounds great and my family been commenting on how good the speakers/room sounds.

The wall top of the speakers was filled with rockwool and measure as i add pcs. I notice as i added rockwool a dip was getting worst between 100-200hz . I remove all rockwool except 8" in the ceiling joist and i left 2" against front wall and added wood slats to keep hi end in the room.


I also notice i had a problem with the height of the speakers so i cut down the stands to make the stand/speakers height a little under 48" from original height of 52" and it was much better.

I still have problems at 80hz and other freqs, I'm thinking the back wall will be the next area i will do later in life but now i will use eq on the remaining problems.











Thanks and forgive me for my grammer.

[OpusOfTrolls]

welcome back denlig.
When you add absorption and a null gets deeper, that is a sure sign the interfering surface is somewhere else. You might want to try freestanding panels made with really loose insulation to break up some reflection paths.

[denlig]

Here's some freq measurements and zip files. Please can the more knowledgeable acoustic heads have a look at the zips and tell me how is the reflection of the measurements looks.

I know i need to tame the low end more and it's with the back wall that's the only part of the studio i haven't reworked yet. So far the sound of the room is great and i will be redoing some old mixes to check translation.


Thanks and sorry for the poor grammer.mixcube group measurement 12-18-2012.zip

new group measurement 12-18-2012.zip

[denlig]

Originally Posted by OpusOfTrolls

welcome back denlig.
When you add absorption and a null gets deeper, that is a sure sign the interfering surface is somewhere else. You might want to try freestanding panels made with really loose insulation to break up some reflection paths.

OpusOfTrolls,

Well when i drop the speakers lower the dip move back up, I'm confused right now.

Can u have a look at the zip files and tell me were u see reflection. I'm lost right now but it sounds awesome in the room but i know it can be a lil better.

Thanks

[OpusOfTrolls]

I don't have rew installed on this computer, but by the graphs shown you are on the right track.

For the KRKs, if you stuff the ports with polyester batting, you can take down the peak around 40hz, get more extension below 40hz, and possibly clean up the mids a bit.

If you drop the speakers and the dip moves up, this is most likely indicating the ceiling and floor reflection distance in regards to the backwall, as the culprit. If you were to treat both ceiling and backwall, you will need really good absorption to hit hard into the dip, at minimum .4 on both surfaces. Try using a less dense rockwool for these surfaces.

[denlig]

Originally Posted by OpusOfTrolls

I don't have rew installed on this computer, but by the graphs shown you are on the right track.

For the KRKs, if you stuff the ports with polyester batting, you can take down the peak around 40hz, get more extension below 40hz, and possibly clean up the mids a bit.

If you drop the speakers and the dip moves up, this is most likely indicating the ceiling and floor as the culprit.

I got the ports stuffed tight with tee shirts and that brought the 40hz down to where it's at now so it's stuffed pretty tight. I will see if i can find some polyester batting and stuff in the ports as see if it get's better.

I also was thinking about removing the amp and seal the port from the inside with particle board glued to the sides and glue around the port but i might get some resonant from the particle board. I'm up for anything except for redoing the walls.

Do the graphic look bad and do u think eq is the next step ?

[OpusOfTrolls]

Originally Posted by denlig

I got the ports stuffed tight with tee shirts and that brought the 40hz down to where it's at now so it's stuffed pretty tight. I will see if i can find some polyester batting and stuff in the ports as see if it get's better.

I also was thinking about removing the amp and seal the port from the inside with particle board glued to the sides and glue around the port but i might get some resonant from the particle board. I'm up for anything except for redoing the walls.

Do the graphic look bad and do u think eq is the next step ?

Woa, slow down. I was only suggesting to plug the ports. If you remove the backplate from the monitor, you will have to add a baffle, and if you permenately rid the port, you might as well cut it out and seal the front baffle.

Are the RP10 amps attached to the backplate?

If you do decide to separate the amps from the cabinets, use the backplate as a drill guide for the new baffle. You might be able to get away with using the same screws, but given the cheap KRK construction, your best bet is to use longer screws and drill pilot holes for them. Use a small enough bit to leave the previous threads intact, because they will hold the new screws in place.

If you don't like the idea of fixing up the walls to get the "perfect room" use large freestanding panels. Figure your specular reflection paths beforehand to keep the room alive.

[denlig]

Originally Posted by OpusOfTrolls

Woa, slow down. I was only suggesting to plug the ports. If you remove the backplate from the monitor, you will have to add a baffle, and if you permenately rid the port, you might as well cut it out and seal the front baffle.

Are the RP10 amps attached to the backplate?

If you do decide to separate the amps from the cabinets, use the backplate as a drill guide for the new baffle. You might be able to get away with using the same screws, but given the cheap KRK construction, your best bet is to use longer screws and drill pilot holes for them. Use a small enough bit to leave the previous threads intact, because they will hold the new screws in place.

If you don't like the idea of fixing up the walls to get the "perfect room" use large freestanding panels. Figure your specular reflection paths beforehand to keep the room alive.

Sorry i didn't mean not putting the amp back. The end of the port stop about 3-4" from the amp plate and at the end of the port inside the box is what i would seal with the particle board and glue. this would be a cleaner way to seal the port and not the stuff port look. Sorry for not explaining better LMAO.

[OpusOfTrolls]

Glue is not worth it IMO. The polyester is more than enough to stop any resonance, and also adds fill to the box to a limited extent. You probably had polyester in your KRKs when you opened them up. And, if you want to have the response of the original ported speakers, you just pull out the polyester.

EQ is certainly an option, but try to get the room well tuned first. EQ will rob headroom from the monitors.

[Glenn Kuras]

I just checked out the files and think they look pretty darn good. The only thing I would consider looking at is the early reflections (view the ETC). You seem to have a few reflections below a 20ms that are above -20db. BTW they are not HORRIBLE but just pointing it out.
Early or First Reflection Points - GIK Acoustics

[denlig]

Originally Posted by Glenn Kuras

I just checked out the files and think they look pretty darn good. The only thing I would consider looking at is the early reflections (view the ETC). You seem to have a few reflections below a 20ms that are above -20db. BTW they are not HORRIBLE but just pointing it out.
Early or First Reflection Points - GIK Acoustics

Glenn,


Thanks for taking the time to look over the files. I can see the reflection in the ETC and will focus on different tilts of the front /back desk and maybe add some acoustic panels at the back of the desk.

This is the first time I've been totally satisfied with the look and sound of my studio in 18 year. I never knew how important room acoustic and speaker placement was to a studio having a great sound.


Thanks to all that helped me on Gearslutz

[denlig]

I'm totally blown away by how good my room sound with the treatment and the proper speakers/placement. The KRK ROKIT 10-3 just sound awesome in the room. All the instruments is so vivid and in your face. I can finally here what my equipment and plug-in sounds like.

I feel alive again in the studio, its hard to explain how things sounds in here. I was remixing some old songs and i could tell right away that the room had clouded my hearing so bad that all some of the songs needed was just slight eq to be complete.

I can truly confess that acoustic treatment/speakers/proper placement has change my life as a studio owner.

Sorry for ranting but i had to tell somebody !!!!

[OpusOfTrolls]

How high is it to the ceiling between the monitors and listening spot?

[denlig]

Originally Posted by OpusOfTrolls

How high is it to the ceiling between the monitors and listening spot?

OpusOfTrolls,

4ft to from top speaker to ceiling.


I have upstairs floor with floor joist with 8" rockwool between joists of the whole ceiling,cover with fabric and 4 wood space couplers 3x3ft with 4" wide openings and 4" deep between the speakers and mix spot.

The whole room floor to ceiling 8ft flat

[OpusOfTrolls]

Would you mind taking another sweep? Lower the KRKs until the bottom of the mid driver is just above the top of the desk.

What are those third pair of monitors btw?

[denlig]

Originally Posted by OpusOfTrolls

Would you mind taking another sweep? Lower the KRKs until the bottom of the mid driver is just above the top of the desk.

What are those third pair of monitors btw?

OpusOfTrolls,

The other pair of speaker is Event ASP Precision 8.One of them is going out so that's why I bought the KRK.

I did measure with lower the speakers sitting on a low table and the measurement was better the lower the speakers. the reason i move them up was the the woofers was fireing under the desk the the frequency was better in the midrange if i remember correctly. I also wasn't sure about other problems that could occur with the speakers that low.


I had one of my computer screen die and other one having problems too. my tech said he can have them fix by Sunday so I will measure again with the speaker lower and post the graphs when the computer screens is fix.

[denlig]

Originally Posted by OpusOfTrolls

Would you mind taking another sweep? Lower the KRKs until the bottom of the mid driver is just above the top of the desk.

What are those third pair of monitors btw?

OpusOfTrolls,


I finally got both my computer screens fix and i did some more test as OpusOfTrolls requested. This time i use my Event ASP 8's and lowered the speaker with the center tweeter at 43" from floor. Here's some of the files to view.


















REW GROUP MEASUREMENT 1-6-2013.zip

[OpusOfTrolls]

Looks great

Build yourself some new stands and set up a monitoring EQ.